stmmac: Configure Flow Control to work correctly based on rxfifo size

Configure flow control correctly, and based on the receive fifo size read
as a property from the devicetree since the Synopsys stmmac fifo sizes are
configurable based on a particular chip's implementation. This patch maintains
the previous incorrect behavior unless the receive fifo size is found in the
devicetree.

Signed-off-by: Vince Bridgers <vbridger@opensource.altera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 40 insertions, 9 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index cd77289c3cfe..623c6ed8764a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -150,7 +150,7 @@ struct stmmac_extra_stats {
 #define MAC_CSR_H_FRQ_MASK      0x20
 
 #define HASH_TABLE_SIZE 64
-#define PAUSE_TIME 0x200
+#define PAUSE_TIME 0xffff
 
 /* Flow Control defines */
 #define FLOW_OFF        0
@@ -357,7 +357,8 @@ struct stmmac_dma_ops {
         void (*dump_regs) (void __iomem *ioaddr);
         /* Set tx/rx threshold in the csr6 register
          * An invalid value enables the store-and-forward mode */
-        void (*dma_mode) (void __iomem *ioaddr, int txmode, int rxmode);
+        void (*dma_mode)(void __iomem *ioaddr, int txmode, int rxmode,
+                         int rxfifosz);
         /* To track extra statistic (if supported) */
         void (*dma_diagnostic_fr) (void *data, struct stmmac_extra_stats *x,
                                    void __iomem *ioaddr);
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
index 59d92e811750..0e8937c1184a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
@@ -106,8 +106,29 @@ static int dwmac1000_dma_init(void __iomem *ioaddr, int pbl, int fb, int mb,
         return 0;
 }
 
+static u32 dwmac1000_configure_fc(u32 csr6, int rxfifosz)
+{
+        csr6 &= ~DMA_CONTROL_RFA_MASK;
+        csr6 &= ~DMA_CONTROL_RFD_MASK;
+
+        /* Leave flow control disabled if receive fifo size is less than
+         * 4K or 0. Otherwise, send XOFF when fifo is 1K less than full,
+         * and send XON when 2K less than full.
+         */
+        if (rxfifosz < 4096) {
+                csr6 &= ~DMA_CONTROL_EFC;
+                pr_debug("GMAC: disabling flow control, rxfifo too small(%d)\n",
+                         rxfifosz);
+        } else {
+                csr6 |= DMA_CONTROL_EFC;
+                csr6 |= RFA_FULL_MINUS_1K;
+                csr6 |= RFD_FULL_MINUS_2K;
+        }
+        return csr6;
+}
+
 static void dwmac1000_dma_operation_mode(void __iomem *ioaddr, int txmode,
-                                         int rxmode)
+                                         int rxmode, int rxfifosz)
 {
         u32 csr6 = readl(ioaddr + DMA_CONTROL);
 
@@ -153,6 +174,9 @@ static void dwmac1000_dma_operation_mode(void __iomem *ioaddr, int txmode,
                         csr6 |= DMA_CONTROL_RTC_128;
         }
 
+        /* Configure flow control based on rx fifo size */
+        csr6 = dwmac1000_configure_fc(csr6, rxfifosz);
+
         writel(csr6, ioaddr + DMA_CONTROL);
 }
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
index 7d1dce9e7ffc..9d0971c1c2ee 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac100_dma.c
@@ -72,7 +72,7 @@ static int dwmac100_dma_init(void __iomem *ioaddr, int pbl, int fb, int mb,
  * control register.
  */
 static void dwmac100_dma_operation_mode(void __iomem *ioaddr, int txmode,
-                                        int rxmode)
+                                        int rxmode, int rxfifosz)
 {
         u32 csr6 = readl(ioaddr + DMA_CONTROL);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 60651738f2a9..05c146f718a3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1277,8 +1277,10 @@ static void free_dma_desc_resources(struct stmmac_priv *priv)
  */
 static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 {
+        int rxfifosz = priv->plat->rx_fifo_size;
+
         if (priv->plat->force_thresh_dma_mode)
-                priv->hw->dma->dma_mode(priv->ioaddr, tc, tc);
+                priv->hw->dma->dma_mode(priv->ioaddr, tc, tc, rxfifosz);
         else if (priv->plat->force_sf_dma_mode || priv->plat->tx_coe) {
                 /*
                  * In case of GMAC, SF mode can be enabled
@@ -1287,10 +1289,12 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
                  * 2) There is no bugged Jumbo frame support
                  *    that needs to not insert csum in the TDES.
                  */
-                priv->hw->dma->dma_mode(priv->ioaddr, SF_DMA_MODE, SF_DMA_MODE);
+                priv->hw->dma->dma_mode(priv->ioaddr, SF_DMA_MODE, SF_DMA_MODE,
+                                        rxfifosz);
                 priv->xstats.threshold = SF_DMA_MODE;
         } else
-                priv->hw->dma->dma_mode(priv->ioaddr, tc, SF_DMA_MODE);
+                priv->hw->dma->dma_mode(priv->ioaddr, tc, SF_DMA_MODE,
+                                        rxfifosz);
 }
 
 /**
@@ -1442,6 +1446,7 @@ static void stmmac_tx_err(struct stmmac_priv *priv)
 static void stmmac_dma_interrupt(struct stmmac_priv *priv)
 {
         int status;
+        int rxfifosz = priv->plat->rx_fifo_size;
 
         status = priv->hw->dma->dma_interrupt(priv->ioaddr, &priv->xstats);
         if (likely((status & handle_rx)) || (status & handle_tx)) {
@@ -1456,10 +1461,11 @@ static void stmmac_dma_interrupt(struct stmmac_priv *priv)
                     (tc <= 256)) {
                         tc += 64;
                         if (priv->plat->force_thresh_dma_mode)
-                                priv->hw->dma->dma_mode(priv->ioaddr, tc, tc);
+                                priv->hw->dma->dma_mode(priv->ioaddr, tc, tc,
+                                                        rxfifosz);
                         else
                                 priv->hw->dma->dma_mode(priv->ioaddr, tc,
-                                        SF_DMA_MODE);
+                                                        SF_DMA_MODE, rxfifosz);
                         priv->xstats.threshold = tc;
                 }
         } else if (unlikely(status == tx_hard_error))